EP2322726B1 - Tuft element - Google Patents

Description

The invention relates to a nub element with a plurality of nubs, which are formed by thermoforming or deep drawing a plastic film, such as a film web or plate, and in any case projecting on one side of the film web or plate.

Nub elements have a flat area and over this protruding, each having a knobbed shell and a knobbed nubs.

Generic nub elements, for example dimpled sheets, are used, inter alia, for building sealing, i. for building protection and drainage, but also for green roofs and as drainage layers, e.g. used for parking or walking and driving paths with lawn grating stones and the like. When building waterproofing they serve as protection of seals in the basement area, to prevent the filling of the pit damage to the seal by the soil and stones. At the same time can be discharged to the basement floor to a drainage pipe by the nub elements laterally to the building inflowing water. In addition to water drainage, a vertically mounted dimpled sheet also fulfills a thermal insulation function. In addition, a protection of the basement walls from soil moisture and appropriate ventilation can be achieved by ventilation. Molded membranes also protect foundations from moisture and contribute to good ventilation (foundation wall protection) and also protect screed floors from rising damp (wet barrier). In the field of green roofs they serve as a protective and drainage layer in the green roof structure and can otherwise be installed both horizontally and vertically.

In any case, such dimpled sheets are exposed to high loads. The nubs are conventionally designed as conical or truncated pyramids, such as from the

DE 10 2006 052 257 A1 or the DE 10 2005 044 800 B3 evident. To increase the rigidity has already been proposed to structure the surface of the knobs, for example by trough-like beads, see. the DE 20 2006 001 699 U1 , However, it has surprisingly been found that by such measures, the deep drawn during deep drawing knobs tend to buckle under pressure, so they lose their support and drainage function as well as the otherwise given sealing function.

A particular problem in this case is the transition region between dimpled casing and dimpled head, which is usually sharp-edged or folded.

Also from the GB 2079415 A is a nub element with ei-ner plurality of each a nub coat and a knobbed nubs, which are formed by thermoforming a plastic film, but can also be produced elsewhere, and project at least on one side of the plastic film, known in which the nubbed jacket at least partially after cambered on the outside. These are hemispherical nubbed elements which do not have high compressive strength. In particular, there is no relatively steep pimpled sheath here. Rather, the nubbed coat extends dome-shaped or vault-shaped, by emerging from the film like a hemisphere. The compressive strength of such nubs or nub elements is severely limited. In addition, only a relatively low construction height and thus only a relatively low drainage effect.

The invention is therefore based on the object to provide a nub element with improved rigidity and dimensional stability. It should be achieved with the same material use a higher load capacity, in particular pressure resistance, and thus a higher drainage capacity and a lower compression behavior.

This object is achieved according to the invention in that the dimpled casing is at least partially cambered to the outside and increasingly tapers toward the knobbed head.

It has been found that the nubs of conventional dimpled sheets essentially buckle just below the dimpled head, ie in the upper region of the dimpled shell. Several investigations have shown that this is due to the fact that in the shaping of the impact-resistant and dimensionally stable plastics, in particular thermoplastic moldable plastics, such as polystyrene (PS), impact-resistant polystyrene (PSI-HI), styrene-butadiene, styrene block Copolymer (SPS), oriented polystyrene (OPS), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene-acrylic ester copolymer (ASA), styrene-acrylonitrile copolymer (SAN), polyvinyl chloride (PVC-U), high density polyethylene (PE-HD), polypropylene (PP), extruded polymethyl methacrylate (PMMA), cast polymethyl methacrylate (PMMA), polycarbonate (PC), polyamide (PA), polyethylene terephthalate (PET-G), polyethylene terephthalate (APET), crystallizable polyethylene terephthalate (CPET) , Polysulfone (PSU) and High Density Polyethylene (HDPE) in the so-called positive process, in which the outer contour of the mold is molded, the material distribution in the corner areas is the lowest. There is a relatively high stretching of the film web or plate, so that sharp-edged transitions between knob shell and head adversely affect the distribution of material in the corners. It is therefore desirable if possible a transition with radii between the two parts.

The distribution of the plastic is generally a problem during deep drawing and thermoforming. If the heated or still warm plastic sheet or foil is pre-stretched and then sucked to the wall with a vacuum (positive method), the result is rapid cooling when it is applied the tool wall in the corner of a cone or truncated pyramid a very thin layer before. It is therefore necessary to design the mold so that the plastic material is distributed as well as possible in all areas in order to achieve the most uniform possible cooling and thus a high compressive strength and a lower compression behavior. This is best achieved by an outwardly convex shape of the dimpled shell, with the dimpled sheath increasingly tapering towards the knobbed head. By a convex or convex bulge of the dimpled mantle and simultaneous tapering, it is particularly well possible then to produce a continuous transition to the dimpled head, which is just as important in achieving the desired high compressive strength with low compression behavior. The knobbed head is preferably formed dome, teilkugel- or teilellipsoidförmig. By such a balloon shape any breaking point between dimpled casing and knobbed head is reduced or avoided. Ideally, the curvature of the dimpled mantle blends seamlessly into the radius of the dimpled head. It is preferable to ensure a steady transition.

In deep-drawing, thermoforming and extruding, the general problem is that there is a relatively large amount of plastic material in the upper area and relatively little material at the bottom of the tool because it is cooled directly on first contact with the tool and only then drawn. Therefore, it is important to design the mold from the outset so that the plastic material is distributed as well as possible. This succeeds according to the investigations carried out best by a balloon-shaped, ie dome, teilkugel or teilellipsoidförmige configuration of the knobbed head.

The limit at which the nub fails altogether and as a bellows is compressed, is significantly influenced by the transitions and radii between the upper, pressure-loaded top surface, so the knobbed head, and the dimpled shell. In addition, the transition region between the lateral surface and the flat region, ie the original film web, from which the nubs are formed by forming, has a corresponding meaning. Again, the optimizations have led to a certain transitional shape, which shifts the triggering of the destructive folding process further towards higher pressure load.

The material can flow freely in the embodiment according to the invention during deep drawing or thermoforming, there is no area that in the positive process by applying to the mold wall particularly fast or faster than other areas cooled down. Thus, the formation of a thin layer, as previously occurred in the corner regularly avoided. The selected measures achieve an improvement in compressive strength and compression behavior of up to 55%.

In an embodiment, it can also be provided that the knob cover merges champfer-shaped, chamfered or obtuse-angled into the knobbed jacket. Such chamfers or chamfers and fillets, for example by 2 x 45 ° degrees, also already facilitate the free flow of the plastic material during deep drawing.

It can further be provided that the dimpled head is flattened at least regionally in order to facilitate application of the dimpled element to a structural waterproofing or laying on of other structural components or laminating, for example nonwovens.

Also claimed is a nub for a nub element with a nub coat and a knobbed head, in which the nubbed casing is at least partially outwardly cambered and increasingly tapers towards the nub head. In design, the knobbed head is steadily over in the knobbed shell. The knobbed head is advantageously formed dome, teilkugel- or teilellipsoidförmig.

Finally, a method for producing a nub element with a plurality of nubs each having a nubbed shell and a knobbed nubs, wherein the nubs are formed by thermoforming or deep drawing in the positive process, claimed, which is characterized in that the nubs by means of a designed as a half ellipsoid Forming tool are formed. It is therefore advisable to use as a mold tool a stamped outward stamp or deep draw the plastic film or plate over a corresponding contoured outwardly cambered tool. The stamp advantageously has a dome, teilkugel- or teilellipsoidförmigen head on. This ensures that a steady transition between studded jacket and knobbed head and a uniform flow of the plastic material can be achieved.

Of course, care must be taken with the curved shape on a sufficient Entformungsschräge. The larger the draft angle, the faster can be removed from the mold, which also shortens the cycle time. In addition, a large draft angle reduces the risk of deformation of the molding during demoulding. In the case of positive forming tools, a draft angle of α = 3 ° to 5 ° should be aimed for. Removal takes place as soon as the thickest point of the molded part has cooled to below the softening temperature. In order to be able to demold safely, the molded part must be stiff enough. The molded part must not be too cold.

Fig. 1

ein erfindungsgemäßes Noppenelement mit verschiedenen Noppen mit nach außen bombierten, sich zum Noppenkopf hin zunehmend verjüngenden Noppenmänteln sowie ballonförmigen und abge- flachten Noppenköpfen,

Fig. 2

einen nach außen bombierten Stempel mit teilellipsoidförmigem Kopf,

Fig. 3

einen nach außen bombierten Stempel mit champferförmigem, teilweise abgeflachtem Kopf,

Fig. 4

einen nach außen bombierten Stempel mit abgeflachtem Kopf mit weitem Radius,

Fig. 5

einen nach außen bombierten Stempel mit abgeflachtem Kopf mit engem Radius.

The invention is explained in more detail below by way of example with reference to the drawing. This shows in:

Fig. 1

a nub element according to the invention with various knobs with knobbed outwardly projecting dimpled shells and balloon-shaped and flattened dimpled heads, which increasingly taper towards the dimpled head,

Fig. 2

an outwardly stamped stamp with teilellipsoidförmigem head,

Fig. 3

an outwardly stamped stamp with champferförmigem, partially flattened head,

Fig. 4

an outwardly stamped stamp with a flattened head with a wide radius,

Fig. 5

an outwardly stamped stamp with a flattened head with a narrow radius.

A nub element, generally designated 1, has a multiplicity of nubs 2 '- 2 ". The nubs 2' - 2", which may be arranged uniformly or non-uniformly, closer or farther apart on the nub element 1, according to the invention have at least in some regions externally cambered knobbed jacket 3, which increasingly tapers towards the knobbed head 4. The nub head 4 is either, as indicated by the reference numeral 4, dome, teilkugel- or teilellipsoidförmig. But it can also - be flattened at least in some cases, in particular at the free tip, otherwise indicated by reference numeral 6 - with otherwise continuous transition 8 between knob shell 3 and knobbed head.

In an embodiment, the knobbed head 4 also champferförmig, chamfered or obtuse, as indicated by the reference numeral 7 in Fig. 3 indicated on the tool stamp, pass into the knobbed jacket 3.

Various forms are conceivable. FIG. 2 shows the perfectly rounded version, in which the fully outwardly cambered nub shell 3, which increasingly tapers in the direction of the nub head 4, steadily merges into the dome, part ball or teilellipsoidförmigen knob head 4.

In FIG. 3 is the knobbed head 4, however, as indicated by reference numeral 6, flattened and is incidentally, as indicated by reference numeral 7, champfer-shaped in the knob head 4 over. Also, further transitions from an outwardly cambered nub shell 3, which increasingly tapers in the direction of the nub head 4, with more or less wide radii 9, as in FIG. 4 indicated, or narrow radii 10, as in FIG. 5 indicated, possible, wherein the knobbed head 4 may in turn be flattened or balloon-shaped, in particular dome, teilkugel- or teilellipsoidförmig.

It is essential for the present invention, on the one hand, that the dimpled casing 3 bulges outwardly, ie is convexed or convex, for example, and increasingly tapers toward the dimpled head 4, and that the dimpled casing 3 merges continuously into the dimpled head 4 and not at a sharp angle. As a result, a uniform material flow is best achieved during deep drawing and too short-term, selective cooling of the plastic film at the first contact with the tool during thermoforming avoided. Finally, it is also possible to achieve an improvement of the compressive strength and a reduction of the compression behavior in that the studs 2 continue to be of frusto-conical shape, as is conventional, but the transition region between the studded jacket 3 and studded head 4 likewise has the largest possible radius is trained.

Of course, the invention is not limited to the illustrated embodiments. Further embodiments are possible without departing from the basic idea. Thus, it is also possible, for example, only subregions 11 ', 11 "of the dimpled shell 3 to be outwardly cambered in the direction of the dimpled head 4 towards increasingly tapering and to draw in other regions 12', 12" in a concave manner, in which case, however, this concave shape only extends over a portion of the height of the dimpled shell 3 extends and ends before the transition region 8 to the knob head 4, to further ensure a smooth and steady transition between knobbed shell 3 and knobbed head 4.

Claims (10)

1. Knob element comprising a plurality of knobs each having a knob walk and a knob head, which knobs are formed by thermoforming a plastics material film and project from at least one side of the plastics material film, characterised in that the knob walk (3) is convex at least in some regions and progressively tapers towards the knob head (4).
2. Knob element according to claim 1, characterised in that the knob head (4) merges continuously into the knob walk (3).
3. Knob element according to claim 1 and/or claim 2, characterised in that the knob head (4) is dome-shaped, part-spherical or part-ellipsoidal in construction.
4. Knob element according to claim 1 and/or at least one of the claims thereafter, characterised in that the knob head (4) is flattened at least in some regions.
5. Knob element according to claim 1, characterised in that the knob head (4) merges into the knob walk (3) in a chamfered, bevelled or obtuse-angled manner.
6. Knob for a knob element comprising a knob walk and a knob head, characterised in that the knob walk (3) is convex and progressively tapers towards the knob head (4).
7. Knob according to claim 6, characterised in that the knob head (4) merges continuously into the knob walk (3).
8. Knob according to claim 6 and/or claim 7, characterised in that the knob head (4) is dome-shaped, part-spherical or part-ellipsoidal in construction.
9. Method for producing a knob element comprising a plurality of knobs each having a knob walk and a knob head, the knobs being formed by thermoforming according to the air-slip method, characterised in that the knobs (2) are formed by means of a moulding tool configured as a semi-ellipsoid.
10. Method according to claim 9, characterised in that a convex die having a dome-shaped, part-spherical or part-ellipsoidal head (4) is used.

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